okay so heres my problem. its now 25-30 below here, and no ones vehicles like to start or run. i had my 97 xj plugged in for 20 hours, and charged the battery at the same time. when i went to start it this morning it was 28 below, and it turned over like it was summer time, and immediately started. it ran for about half a second, then died. after numerous attempts it cranked and cranked, and had no signs of firing. my truck usually starts in this temperatures, so this is unusual for me. could there be condensation in my fuel lines, which has now frozen? any help or comments are appreciated!

it is likley that moisture in your fuel lines is frozen,Do you have a fuel pressure tester?check it if you can and see if it has pressure. if not try and park it somwhere so it can warm up again,do not use a tourch,sorry to mention that but some folks have tried with less than desirable results.
I have not use them but I think there are some additives to prevent this.

i was going to throw in a bottle of gas line antifreeze, but its doubtful it will make its way from the fuel tank asll the way to the fuel rail.

You are probably correct,i doubt you want to remove the lines to check them and to get them to a warm place,I think you need to thaw them out.
But this is coming from someone that has never seen temps you have.

aww crap, its supposed to be quite cold for the next week. good thing my old 84 starts in this weather. i think the 2.8 is so worn out it doesnt get affected by cold weather